Caustic stannate-urea treatment of cotton fabrics



Patented Oct. 24, 1950 CAUSTIC STANNATE-UREA TREATMENT OF COTTON FABRICS Charles L. Mantell, Manhasset, and Oscar K. Heim, VVoodside, N. Y., assignors to United Merchants & Manufacturers, Inc., Wilmington, Del, a corporation of Delaware No Drawing. Application January 10, 1949, Serial No. 70,148

8 Claims.

This invention relates to the treatment of cotton fabric and has for its primary object a method of modifying the shrinkage of woven or knitted cotton cloth to the end of producing a fabric of enhanced value and utility, the method requiring no complicated or special equipment for its practice and being otherwise economical to carry out. As hereinafter described in greater detail, the invention contemplates the treatment of the fabric with a solution which, in more or less noticeable degree according to the character of the fabric and the method employed, modifies the shrinkage characteristics of the fabric, and renders the fabic somewhat stiffer.

The invention essentially comprises a process of treating cotton fabric with a solution containing caustic stannate and urea, there being obtained a fabric having appreciably modified shrinkage characteristics; that is, it shows a substantially reduced shrinkage by comparison with. the normal shrinkage of the untreated fabric, considering such normal shrinkage to be the initial wash shrinkage. It has further been observed that the treated fabric tends to become stiffer by comparison with the untreated fabric, a characteristic which is quite desirable in certain materials, for example in curtain and table goods.

As described, the treating solution is composed of caustic stannate and urea. It may be prepared by mixing together an aqueous solution of sodium stannate and urea; or by adding hydrated or precipitated stannic oxide to an aqueous solution of sodium hydroxide, sodium stannate being formed, and then incorporating the urea. Besides the sodium compounds, compounds of other alkali metals may be used, such as potassium stannate, or potassium hydroxide, although sodium compounds are preferred. It is to be understood that in referring to the stannic oxide content of the solution, it is intended to include the oxide added as such or as comprised in the alkali metal stannate added to the solution or formed therein. The amount of urea generally used is about by weight. At concentrations substantially below this amount, the solution has decreased effects, while at higher concentrations no worth-while improvements result. Stannic oxide, whether added as such or in the form of the stannate may be present in amounts ranging from about 1 to about 3% by weight, calculated as stannic oxide. Preferably, it is added in the form of sodium stannate (technical grade, 44% as S1102), in amounts ranging from about 2 to about 6% by weight. The caustic may be varied from about 10 to 22% by weight. The effects are decreased by going below the minimum concentrations of the latter materials; above the maximum concentrations given, there is no worthwhile improvement in results. A preferred solution is one containing about 10% urea, about 1.5% stannic oxide, and about 17% caustic.

The weight relations of the sodium stannate referred to in the specification and claims are based on the commercial material known as sodium stannate which contains about 44% of S1102, rather than on the compound represented by the formula Na2Sl'1O3. Material of other concentrations of SnO2 may, of course, be employed. care being had to maintain an overall amount of S1102 of between about 1% and about 3%.

. Application of the solution to the fabric is done by simply pouring it on the fabric, although usually it is better to rub it on, either manually or by means of knives or doctor blades. Mangle eouipment, such as padders or quetches, are useful for this purpose as is also pressure equipment like rollers. Jigs and rolls are likewise suitable. The time of treatment may range from about 10 seconds to about 2 minutes, while the temperature is generally room temperature, although, of course, higher and lower temperatures may be employed. After treating, the fabric is framed 'to its original width, preferably on a tenter frame.

It is then washed, neutralized with dilute acid, and rinsed with water, either in the stretched or unstretched condition. Thereafter it is frame dried.

In practicing the invention, it is generally desirable to pretreat the fabric to be stabilized with a chemical degradation agent and then with the solution as above described. The object of the degradation step is to render the cloth more susceptible to the action of the solution, but care must be exercised to limit the amount of degradation. To this end the strength of the agent and the time and temperature of its application a bleaching compound such as the alkali and alkaline earth metal hypochlorites, of which group sodium hypochlorite is a preferred material, hy pochlorous acid, and sodium chlorite. Hydrogen peroxide, or ammonium persulphate, which are conventional bleaching agents, are useful, as is a combination of sodium peroxide, or other alkali metal and alkaline earth metal peroxide, and sulfuric acid. Sodium peroxide may be employed with other acids, such as boric acid, and may be used alone, as may sodium perborate which breaks down to yield the peroxide. Other agents include oxidizing materials such as permanganate and bichromate alone or in conjunction with sulfuric, oxalic, or other acids.

In the case of the chlorine-containing agents, the strength of the solution should not be below 0.1% available chlorine. Stronger solutions may be used, going up to or or higher. Whatever concentration is employed, it must be correlated with the treating time and the temperature. Thus, using sodium hypochlorite, it has been found that the hypochlorite has a twofold effect on the fabric: it lowers the shrinkage, and it decreases the tensile strength. The most stabilized cloth, i. e., having the lowest shrinkage, is attained with a solution containing about 0.1 available chlorine, and this effect remains constant as the concentration of available chlorine is increased. It may be said, therefore, that the stabilization of the cloth is independent of the available chlorine concentration when the latter is above 0.1%. Preferred treating temperatures range from room temperature to about 80 F. although higher or lower temperatures may be used. Treating periods may range from to 60 minutes. In the case of hypochlorite, for example, illustrative operating conditions would be as follows: temperature, C.; treating time, minutes; available chlorine concentration 0.1 to 2.3%.

The concentrations of the other degradation agents will, of course, be different from those obtaining in the case of hypochlorite, and will also vary among themselves, depending upon the agent and the particular treating conditions employed. Therefore no general numerical range covering them collectively can be given in terms of concentration, but for all of them the concentration must be such as not to effect an excessive overall loss in tensile s.rength. Preferably, the loss should not exceed 25% of the strength. Such concentrations, as indicated, will vary with the temperature and the time of treatment, lower concentrations being suitable with longer times and higher temperatures, and vice versa.

In applying the degradation agent to the cloth, the latter is maintained in an unstretched condition and may be impregnated with a solution of the agent or immersed therein. When immersion is employed, the cloth may be agitated in the solution. The cloth may then be washed, and thereafter it is carefully dried and framed to its original width.

Following the pretreatment or degradation step, the cloth is subjected to the action of the caustic stannate urea solution according to the method above described. The following example shows the shrinkage effects of a number of such solutions of varying concentrations:

Example A series of runs were made in which conventionally kier boiled cotton marquisette cloth (unstretched) in 3.5 gm. pieces were tumbled at 25 C. for 30 minutes in a sodium hypochlorite solution having 0.1% available chlorine. The goods were then washed with cold water, rinsed with 1% hydrosulfite solution (antichlor) and then water again. Each sample was dried at 220 F. for about 2 minutes, framed to its original width, and saturated with a caustic stannate urea solution. Each was then placed in a current of hot air until the material felt just dry, rinsed in water at about 100 F., washed with cold 5% acetic acid, and finally with water until neutral. The

samples were then dried at about 220 F., removed from the stretching frame, and subjected to stiffness and shrinkage tests. Following are the results:

Solution Composition Shrinkage SUI 1 Run No. ness NaOH NaiSnO; Urea Warp Filling Original Per cent Per cent Per cent Per cent Grams Clo c 0.05 3 1O 6. 10.5 l2 2 l0 4. 5 6. l ll 7. 5 l0 5. 0 5. 6 07 2 10 5.1 5. 5 .09 4 l0 5. 4 6.0 .07

The shrinkages reported were obtained according to A. S. T. M. D437-36. Stiffness is reported as the force in grams exerted by the sample when bent to a 40 angle.

This application is a continuatoin of copending application Serial Number 616,452, filed September 14, 1945, now abandoned.

In the light of the foregoing description, the following is claimed:

1. Process of inhibiting the wash shrinkage of cotton fabric which comprises treating said fabric with an aqueous solution made from about 10% by weight of urea, about 1 to about 3% by weight of stannic oxide, and about 10 to about 22% by weight of alkali metal hydroxide for a time ranging from about 10 seconds to about 2 minutes, framing the fabric to its original width after said treatment, washing said solution from the fabric and drying the fabric while framed to its original width.

2. Process of inhibiting the wash shrinkage of cotton fabric which comprises subjecting said fabric in unstretched condition to the action of an oxidizing agent to obtain a partial degradation of the fabric, treating said fabric with an aqueous solution comprising about 10% by weight of urea, about 1 to about 3% by weight of stannic oxide, and about 10 to about 22% by Weight of sodium hydroxide for a time ranging from about 10 seconds to about 2 minutes, framing the fabric to its original width after said treatment, washing said solution from the fabric, and drying the fabric while framed to its original width.

3. Process of inhibiting the wash shrinkage of cotton fabric which comprises subjecting said fabric in unstretched condition to the action of an oxidizing agent to obtain a partial degradation of the fabric, and thereafter treating said fabric with an aqueous solution composed of about 10% by weight of urea, about 1 to about 3% by weight of stannic oxide, and about 10 to about 22% by Weight of alkali metal hydroxide for a time ranging from about 10 seconds to about two minutes, washing the solution from the fabric, and drying the fabric under tension.

4. Process of inhibiting the wash shrinkage of cotton fabric which comprises subjecting said fabric in unstretched condition to the action of an oxidizing agent to obtain a partial degradation of the fabric, treating said fabric with an aqueous solution comprising about 10% by weight of urea, about 1 to about 3% by weight of stannic oxide, and about 10 to about 22% 3y weight of alkali metal hydroxide for a time ranging from about 10 seconds to about 2 minutes, framing the fabric to its original width after said treatment, washing said solution from the fabric, and drying the fabric while framed to its original width.

5. Process of inhibiting the wash shrinkage of cotton fabric which comprises treating said fabric 5 with an aqueous solution composed of about 10% by weight of urea, about 1 to about 3% by weight of stannic oxide, and about 10 to about 22% by weight of alkali metal hydroxide for a time ranging from 'about 10 seconds to about two minutes, 5

1 in which the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,630,365 Weber May 31, 1927 FOREIGN PATENTS 10 Number Country Date f16,843 Great Britain Jan. 12, 1940 CHARLES LL MANTELL. 15 I OSCAR K. 

1. PROCESS OF INHIBITING THE WASH SHRINKAGE OF COTTON FABRIC WHICH COMPRISES TREATING SAID FABRIC WITH AN AQUEOUS SOLUTION MADE FROM ABOUT 10% BY WEIGHT OF UREA, ABOUT 1 TO ABOUT 3% BY WEIGHT OF STANNIC OXIDE, AND ABOUT 10 TO ABOUT 22% BY WEIGHT OF ALKALI METAL HYDROXIDE FOR A TIME RANGING FROM ABOUT 10 SECONDS TO ABOUT 2 MINUTES, FRAMING THE FABRIC TO ITS ORIGINAL WIDTH AFTER SAID TREATMENT, WASHING SAID SOLUTION FROM THE FABRIC AND DRYING THE FABRIC WHILE FRAMED TO ITS ORIGINAL WIDTH. 